Glues fabricated from slaughterhouse blood have been known for quite some time. For example, U.S. Pat. No. 1,976,436, issued on Oct. 9, 1934, describes the use of animal blood as a component of wet glues for hot-press forming of plywood sheeting. At that time, the hot-press process was becoming increasingly rare because the process could not be scaled-up economically. Additionally, coniferous woods are not amenable to hot-pressing with a wet blood glue because the wood sheets do not have sufficient porosity to allow the moisture to escape. Thus, when using wet blood glues and hot-pressing, the finished product had unacceptable blistering and checkering of the sheet surfaces due to steam bubbles trapped within the laminate structure. U.S. Pat. No. 1,976,436 describes a blood glue suitable for both hot-press and cold-press forming of plywood sheets. The typical formulation contains 100 parts dried blood, 8 parts NaOH, 7 parts lime, 30 parts sodium silicate and 675 to 725 parts water. The blood component is dehydrated, and the water is added back to ensure the proper ratio of the ingredients in the final glue formulation.
U.S. Pat. No. 2,400,541, issued May 21, 1946, describes a similar dried-blood glue formulation. Again, the glue is described in the context of making plywood sheeting. The typical formulation contains 100 parts dried blood, 9 parts NaOH, 8 parts lime, 40 parts silicate, and 650 part water. The dried blood and water are first mixed and heated to near-boiling. The NaOH is then added in batches, with mixing, and continued heating for another 20 minutes. This glue base is then allowed to cool to room temperature. The remaining ingredients are then added with stirring to yield the final glue product.
Yet another dried blood glue is described in U.S. Pat. No. 2,874,134, issued Feb. 17, 1959. Here, the glue formulation uses soluble, dried, uncoagulated blood. The dried, soluble blood is dispersed in water and heated to about 120° F. The mixture is cooled and sodium silicate and an anti-foaming agent (pine oil) are added. Wheat flour is then added with mixing. Lastly, thermosetting melamine-formaldehyde is added to yield the final glue product. Additional water may also be added at this point to yield a glue of desired viscosity.
In more recent work, U.S. Pat. No. 4,180,412, issued Dec. 25, 1979, describes a method for manufacturing a glue in which physico-chemically altered animal blood is used as a binding agent to make cellulose-containing chipboard or plywood veneer. In this approach, whole blood is treated with an anti-coagulant. The blood is then mixed with a monobasic organic acid in an amount sufficient to yield a mixture having a pH of between 3.0 and 4.0. The preferred acids are acetic acid, propionic acid, formic acid, lactic acid, n-butyric acid, n-valeric acid, n-caproic acid, n-heptoic acid, and mixtures thereof. The whole blood and the acid may be simultaneously mixed and applied using a mixing spray head.
U.S. Pat. No. 4,333,767, issued Jun. 8, 1982, describes a very similar method of making blood-based glue. Here, the animal blood is dried and stored as a dried mass of blood. The dried mass of blood is then converted to a sprayable solution of up to 40% concentration by adding water. The ready-to-use adhesive is prepared by spray-mixing a monobasic organic acid with the liquid blood base. The blood, however, must be dried, a task that can be accomplished via vacuum drying, freeze drying or drying through atomization.
A consistent issue in using animal blood as a glue component is that the blood usually must be dried prior to use. Because fresh, raw blood contains a very large proportion of water, the drying step makes using blood less economical due to the energy cost required to dry the blood prior to use.